THE ARTERIES 137 



(4) Two or three branches are given off to the pterygoid 

 muscles. 



(5) The posterior -'eep temporal artery. — This vessel is also 

 given off before the incernal maxillary artery enters the sub- 

 sphenoidal canal. It ascends to supply the temporal muscle. 



(6) The anterior deep temporal branch is given off in the 

 subsphenoidal canal, which it leaves by passing through the 

 temporal foramen to the temporal muscle, which it supplies. 



(7) The ophthalmic artery also leaves the internal maxillary 

 whilst the latter is in the canal. It passes out through 

 the foramen rotundum with the internal maxillary. The 

 ophthalmic artery then crosses the back of the orbit, and 

 passes between the superior rectus and retractor oculi muscles 

 to enter the cranial cavity by the internal orbital foramen. 

 In the cranial cavity it divides into meningeal and nasal 

 branches. 



Collateral Branches of the Ophthalmic Artery. 



{a) The supra-orbital., which passes out through the supra- 

 orbital foramen, and supplies the upper eyelid and the region 

 of the nasal canthus. 



{b) The lachrymal branch, which is distributed to the 

 lachrymal gland. 



(c) Numerous muscular branches to the muscles of the 

 eyeball. 



{d) The ciliary branches. 



(e) The central artery of the retina which pierces the sclerotic 

 coat with the optic nerve in the axis of which the artery is 

 placed. 



Terminal Branches of the Ophthalmic Artery. 



[a) The meningeal branch gives off branches to the dura 



